In one embodiment of the invention a dispersion compensator is provided for use in a dense wavelength division multiplexed optical communication system. The dispersion compensator comprises a periodic-group-delay dispersion compensation module which provides a portion of the dispersion

A new dispersion managed soliton transmission system where the D map period is the same as the amplifier period and the pulse breathing the in the +D sections of the D maps is approximately symmetrical. Pulse breathing symmetry by one or both of two techniques. In one technique a gui

Method and apparatus for synchronizing two different types of modulators in an optical transmission system includes a first modulator generating an optical pulse train, a second modulator encoding data onto the optical pulse train, an optical filter resolving upper and lower modulation

A nonlinear phase-shift compensation method and apparatus is provided for improving system performance in optical transmission systems. The apparatus includes a phase-shift compensating device that provides a partial compensating phase shift to reduce the nonlinear phase noise result

Techniques are described for constructing an optical fiber transmission line having a desired length and path-average dispersion, while also having a desired total ##EQU1##In one approach, a first fiber is selected with a first dispersion and ##EQU2##and a second fiber is selected wi

By urging an ordinary single-mode (usually dispersion-shifted) fiber into an external, long period mechanical grating, a highly wavelength-selective coupling between the fiber's guiding mode and a cladding mode is induced. A sequence of such induced gratings, all on the same fiber, can b

A dispersion-tapered fiber for use in a soliton transmission system having lumped amplifiers to substantially reduce loss associated with pseudo phase matching and to relax the limitations on minimum allowable channel spacing caused by cross-phase modulation. The dispersion tapered fiber

A system and method in which the chromatic dispersion characteristic, as a function of distance along a section of transmissive fiber, is measured. First and second optical signals are launched into a fiber under test to thereby generate, by a four-wave mixing process in the fiber, a pro

A clock recovery circuit for following rapid changes in the time phase of a data stream is disclosed. The circuit comprises a low Q resonator coupled to a detection device, such as an electro-optic modulator in a time division demultiplexer or a decision circuit of a receiver. Preferably

An improved optical loop mirror is used in an optical demultiplexer to demultiplex time division multiplexed optical communications channels. High bit-rate optical pulses representing a plurality of time division multiplexed communications channels are input to a 3 dB coupler in an o

The disclosed distributed feedback laser employs an alkali halide crystal having a spatially modulated pattern of a stable color center and a complementary spatially modulated pattern of U-centers. The stability of the color centers is provided by initial additive coloration, conversion

Broadly tunable infrared lasers analogous to dye lasers operating in the visible spectrum are provided by significant improvements upon an F.sub.A (II) color center laser previously demonstrated in a limited way. The improvements include techniques for also using F.sub.B (II) and F.sub.2